Unit 6- Human Physiology

Digestive System

breaks down food into small particles that can be absorbed by the body

Alimentary Canal

structures of the digestive system form a "tube" called the...

Mouth, esophagus, stomach, small intestine, gallbladder, pancreas, liver, large intestine

Major structures of the digestive system

Gallbladder, pancreas. liver

accessory organs of the digestive system

Accessory Organs

aid in digestion, but food doesn't pass through them

Mouth

chewing mechanisms digest food, which increases surface area

Esophagus

transports food to stomach via peristalsis

Stomach

churns food and has acidic environment that kills pathogens and activates enzymes

Small intestine

has enzymes that chemically digest biomolecules; wall absobrs small molecules

Liver

secretes bile

Gallbladder

stores and regulates bile

Pancreas

secretes lipase, amylase, and protease

Large intestine

absorbs water and compacts waste to form feces

Peristalsis

a wave of muscle contractions that push food through the gut and mixes it with enzymes

Circular muscles

contract to prevent food from moving backwards

Longitudinal muscles

contract to push food forward down the small intestine tract

Amylase, lipase, protease

enzymes secreted by the pancreas

Starch/glycogen

Substrate of amylase

Maltose

Product of amylase-starch reaction

Triglycerides

Substrate of lipase

Fatty acids and monoglycerides

Product of lipase-triglyceride reaction

Proteins

Substrate of protease

Shorter polypeptides

Product of protease-protein reaction

Be able to label the digestive system

Hydrolysis

Enzymes break macromolecules into monomers that can be absorbed by the intestinal wall. Through what process is this completed?

Proteins

Substrate of peptidase

Amino acids

Product of peptidase-protein reaction

Nucleic acids (DNA?RNA)

Substrate of nuclease

Nucleotides

Product of nuclease-nucleic acids reaction

No. It serves to push substances through the intestine and is the primary component of dietary fiber supplements.

Is cellulose digested?

Absorption

the process of taking substances into cells

The small intestine

Where does absoprtion mostly take place?

Surface area available

What does the rate of absorption depend on?

Villi

finger-like projections of the mucosa that line the inner intestine wall.

A factor of 10

By how much do villi increase surface area?

Thin epithelium and network of capillaries.

Adaptations of the villi that make it suited for absorption

Small intestine

Where do enzymes digest most macromolecules?

Maltose

Substrate of Maltase

Glucose

Product of Maltase-Maltose reaction

Lactose

Substrate of Lactase

Glucose and galactose

Product of lactase-lactose reaction

Sucrose

Substrate of sucrase

Glucose and fructose

Product of sucrase-sucrose reaction

Dipeptides

Substrate of dipeptidase

Amino acids

Product of dipeptidase-dipeptide reaction

Relatively basic (8-14)

What is the optimal pH for digestive enzymes?

Monosaccharides (glucose, fructose, sucrose), amino acids, fatty acids, nitrogenous bases, calcium, potassium, sodium, vitamins

What is absorbed by the villi?

Diffusion

All nutrients except glucose and amino acids enter the villus through the epithelium by ...

Facilitated diffusion

Glucose molecules move into the capillaries by...

Exocytosis

How are lipoproteins excreted?

Mucosa, Sub-mucosa, longitudinal, circular, serosa

Layers of the small intestine

Glucose Transport

Na+/K+ pumps decrease internal concentration of Na+. Na/glucose co-transporters transport glucose into the cells along with Na+. Channel proteins allow glucose to diffuse out of the other side of the cell. Glucose then diffuses into capillaries through small pores.

Glucose absorbed in the capillaries travels to the liver through the hepatic vein. In the liver, cells concert extra glucose into glycogen which can be stored for later use.

How is glucose stores in the liver?

Circulatory system

organ system responsible for transporting oxygen and nutrients around the body as well as removing waste from tissue cells.

Heart

central organ of the ciculatory system

He tied a ligature on the upper arm of a person, which distended the veins in the forearm and made the valves of the forearm clearly visible. He tried to force blood in a vein down the forearm, but to no avail. When he tried to push it up the arm, it moved easilt. Harvey proved that the venous blood flowed to the heart and that the body's valvues in the veins maintained the one-way flow

Outline William Harvey's experiment

Atrium

receives blood from lungs/body

Ventricle

receives blood from an atrium and pumps it out of the heart through arteries

Valves

prevent backward flow

Atrioventricular

between atria and ventricles

Semi-lunar

between ventricles and arteries

Pulmonary artery

carries blood from the heart to the lungs

Pulmonary vein

receives blood back from the lungs

Aorta

carries blood out of the heart to the body

Coronary artery

delivers blood to heart tissue

Vena cava

receives blood from body

Arteries

blood vessels that carry oxygenated blood (expect for pulmonary) away from the heart to cells in the body

High

pressure in arteries

Tunica externa

a tough outer layer of connective tissue

Tunica media

a thick layer containing smooth muscle and elastic fibers

Tunica intima

a smooth endothelium forming the lining of the artery

Elastic fibers recoil after each heart pump, which helps push blood forward. The muscle fibers are able to contract and change the size of the lumen, allowing arteries to control the pressure of blood flowing through them. oth fiber types make arteries "tough," allowing them to withstand high pressures without bulging.

Purpose of muscle and elastic fibers

Capillaries

the smallest blood vessel and form a network through almost all the tissues in the body. Transport and remove substances from cells and so all active cells are close to one.

One cell

How thick is the wall of a capillary?

Yes

Do capillaries have pores?

Veins

transport blood back towards the heart.

Not as high as arteries

Pressure in veins

Valves

Veins contain

Know how to describe blood circulation in the hear

Pulmonary circulation

to and from the lungs

Systemic circulation

to and from all other organs, including heart muscles

Atherosclerosis

occurs when fatty tissues develop in artery walls and muscle walls form a cap over them. This reduces the size of the lumen and impedes blood flow.

Overeating, obesity, diabetes, smoking, stress

Potential causes of atherosclerosis

Coronary Occlsion

occurs when buildup in the artery prevents its ability to deliver oxygen and nutrients. Cases heart pain and increased heart rate.

Sinoatrial node

group of specialized cells that initiates the heartbeat. Located in the right atrium and serves as the heart's pacemaker. This is done without neurons.

Myogenic

the ability to initiate a heartbeat without neurons

Medulla

has a cardiovascular center that is connected to teh heart via two nerves. One signals to decrease the heart rate while the other signals to increase

Blood pressure, oxygen concentration, pH

Heart rate changes depending on...

Epinephrine

secreted by the adrenal glands when vigorous physical activity may be needed and communicate with the SA node

Immune System

organ system responsible for defending the body against infection

Pathogens

cells that are able to cause disease. They are found in the environment and can also live on our skin.

Skin and mucous

What is the body's first line of defense against disease?

Skin

Protects external structures. Thick, dry, and composed predominantly of dead cells. Glands secrete chemicals to restrict bacterial growth.

Mucous

Protects internal structures. Thin region composed of living cells that secrete fluid (mucous) to trap pathogens (which may then be removed)

Platelets

small cell fragments that flow in the blood. When the skin is cut, they gather at the damaged site. They then release clotting factors, which initiate the blood clotting process.

Thrombin

What is prothrombin activated into when clotting factors are released?

Fibrin

What does thrombin convert fibrinogen into?

Fibrin

Insoluble and forms a mesh at the wound site where the platelets are

Red blood cells and small particles getting stuck

What creates the "gel" that seals the wound?

Coronary thrombosis

a blood clot that forms in the coronary artery. As a result, tissues in the heart wall do not receive enough oxygen or nutrients